I have to agree with Martin Giles when he states he has seen no evidence of Blenheims being used to sow (sea) mines or ‘vegetables’ as we know them, the subject of the books mentioned and which were laid by many other types of aircraft.
I believe the nearest weapon carried by a Blenheim would be the ‘W’ Bomb. I cannot recall ever seeing a good description of this device, but in 1940 I have seen many references to ‘W’ Bombs being used, especially by Hampden squadrons, against inland waterways. Many attacks were made with ‘W’ Bombs against canals, or more specifically I think against the canal locks. However, I have no idea how they functioned. Hopefully someone knows more on this topic. It seems a Blenheim could carry at least two ‘W’ Bombs, so these weapons were unlikely to have been very large.
On the subject of the three Blenheims mentioned above I have to query the reliability of the sources used.
1/ Blenheim L8789 of 53 Squadron on 6 July 1940. The 53 Sqn. ORB specifically records that five aircraft of the unit used ‘W’ Bombs against the Ijmuiden-Amsterdam canal (‘Operation 36’, during the night of July 6/7th).
2/ Blenheim R3841 of 18 Sqn. on 15 April 1941. The 18 Sqn. ORB records eight of their aircraft took off between 12.45 and 1.45 p.m. on anti-shipping sorties and it specifically notes the bomb load carried for all as 4 x 250 lb. and 2 x 500 lb. General Purpose bombs.
3/ Blenheim V6176 of 139 Sqn. on 30 July 1941. The 139 Sqn. ORB notes 12 Blenheims took off at 2.00 p.m. with the target for all described as ‘
Towns and targets in NW Germany’. The eight surviving crews all abandoned their missions due to lack of cloud cover, but at least five of them attacked shipping instead. Four were lost to Bf 110s over the North Sea, including V6176.
Published works by Chorley, Warner and Boiten all record these aircraft were on anti-shipping sorties in daylight, with one Blenheim in one book described as being on a reconnaissance flight. Not one mention anywhere of mines or mine-laying.
Regards,
Martin Gleeson.
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